From nobody Tue Nov 26 03:27:28 2024 Received: from smtp-bc09.mail.infomaniak.ch (smtp-bc09.mail.infomaniak.ch [45.157.188.9]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1B8174A18 for ; Tue, 22 Oct 2024 15:20:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.157.188.9 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729610419; cv=none; b=dxdzkbl4amoBjjxR4ZripYQrnBK9omScdbBXsrHHm0IEpio0736Y1t7X/hDt8CwomTuo2BkeRL2xqwYgbIm9Rpmu0c7xovRS4bCFXByUhh7Jk28NTbM/AaWvmuFiRmJKmPI+kKdp3voQBt3/fErYQ3xpz613WFKuxBmeBaTS+gQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729610419; c=relaxed/simple; bh=FFWS8ppweNfThpQsCDSh22hFJ8GHB6BfnvDXD70Q/fs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=TgRTGZB/l7LtRJMJUiCBe4K42erGihDI8/s7p0fwZ75oTns/dwa0SmoRjk/tZNsPflE5TAm1ObgraHnTmBiR0xDzs7xJzjQI43ewwRY/V5R8sQdSCIqCcrdxLa6XBXcv6arbqa9d+wb4KDW2fFogbdsAcX7RezvPFyfIK+1lpDY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=digikod.net; spf=pass smtp.mailfrom=digikod.net; dkim=pass (1024-bit key) header.d=digikod.net header.i=@digikod.net header.b=H2C7Y1Ay; arc=none smtp.client-ip=45.157.188.9 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=digikod.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=digikod.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=digikod.net header.i=@digikod.net header.b="H2C7Y1Ay" Received: from smtp-4-0001.mail.infomaniak.ch (smtp-4-0001.mail.infomaniak.ch [10.7.10.108]) by smtp-4-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 4XXwd43WKmzksN; Tue, 22 Oct 2024 17:11:52 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=digikod.net; s=20191114; t=1729609912; bh=gytrrwHk0gzSPEN5tIehpljuS72vEBMQ53w6/u9Ro3A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=H2C7Y1Aynh7/Pw+jf2fY8qKkyv9cJU+rNeqBm0h+lFIOhsO5JZWZjJZGGq3Dk7Icj Rm39MlWWmTj8Hc0XNDLOLXjwUaOvy8gyoTBgsNO/wxecrk1u7LnF5Tlna1eewVV/KK f7rO8Fn36aUdS5oag9Z3eqPBw84er9R1Bvqs/as0= Received: from unknown by smtp-4-0001.mail.infomaniak.ch (Postfix) with ESMTPA id 4XXwd40Drzzrgd; Tue, 22 Oct 2024 17:11:52 +0200 (CEST) From: =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= To: =?UTF-8?q?G=C3=BCnther=20Noack?= , Mikhail Ivanov Cc: =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= , Konstantin Meskhidze , Paul Moore , Tahera Fahimi , linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH v3 1/3] landlock: Refactor filesystem access mask management Date: Tue, 22 Oct 2024 17:11:42 +0200 Message-ID: <20241022151144.872797-2-mic@digikod.net> In-Reply-To: <20241022151144.872797-1-mic@digikod.net> References: <20241022151144.872797-1-mic@digikod.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Infomaniak-Routing: alpha Replace get_raw_handled_fs_accesses() with a generic landlock_merge_access_masks(), and replace get_fs_domain() with a generic landlock_match_ruleset(). These helpers will also be useful for other types of access. Cc: G=C3=BCnther Noack Cc: Mikhail Ivanov Signed-off-by: Micka=C3=ABl Sala=C3=BCn Link: https://lore.kernel.org/r/20241022151144.872797-2-mic@digikod.net --- Changes since v2: * Create a new type union access_masks_all instead of changing struct acces_masks. * Replace get_fs_domain() with an explicit call to landlock_match_ruleset(). Changes since v1: * Rename landlock_filter_access_masks() to landlock_match_ruleset(). * Rename local variables from domain to ruleset to mach helpers' semantic. We'll rename and move these helpers when we'll have a dedicated domain struct type. * Rename the all_fs mask to any_fs. * Add documentation, as suggested by G=C3=BCnther. --- security/landlock/fs.c | 31 ++++------------ security/landlock/ruleset.h | 70 +++++++++++++++++++++++++++++++----- security/landlock/syscalls.c | 2 +- 3 files changed, 70 insertions(+), 33 deletions(-) diff --git a/security/landlock/fs.c b/security/landlock/fs.c index 7d79fc8abe21..dd9a7297ea4e 100644 --- a/security/landlock/fs.c +++ b/security/landlock/fs.c @@ -388,38 +388,21 @@ static bool is_nouser_or_private(const struct dentry = *dentry) unlikely(IS_PRIVATE(d_backing_inode(dentry)))); } =20 -static access_mask_t -get_raw_handled_fs_accesses(const struct landlock_ruleset *const domain) -{ - access_mask_t access_dom =3D 0; - size_t layer_level; - - for (layer_level =3D 0; layer_level < domain->num_layers; layer_level++) - access_dom |=3D - landlock_get_raw_fs_access_mask(domain, layer_level); - return access_dom; -} - static access_mask_t get_handled_fs_accesses(const struct landlock_ruleset *const domain) { /* Handles all initially denied by default access rights. */ - return get_raw_handled_fs_accesses(domain) | + return landlock_merge_access_masks(domain).fs | LANDLOCK_ACCESS_FS_INITIALLY_DENIED; } =20 -static const struct landlock_ruleset * -get_fs_domain(const struct landlock_ruleset *const domain) -{ - if (!domain || !get_raw_handled_fs_accesses(domain)) - return NULL; - - return domain; -} +static const struct access_masks any_fs =3D { + .fs =3D ~0, +}; =20 static const struct landlock_ruleset *get_current_fs_domain(void) { - return get_fs_domain(landlock_get_current_domain()); + return landlock_match_ruleset(landlock_get_current_domain(), any_fs); } =20 /* @@ -1516,8 +1499,8 @@ static int hook_file_open(struct file *const file) layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] =3D {}; access_mask_t open_access_request, full_access_request, allowed_access, optional_access; - const struct landlock_ruleset *const dom =3D - get_fs_domain(landlock_cred(file->f_cred)->domain); + const struct landlock_ruleset *const dom =3D landlock_match_ruleset( + landlock_cred(file->f_cred)->domain, any_fs); =20 if (!dom) return 0; diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h index 61bdbc550172..e00edcb38c5b 100644 --- a/security/landlock/ruleset.h +++ b/security/landlock/ruleset.h @@ -47,6 +47,15 @@ struct access_masks { access_mask_t scope : LANDLOCK_NUM_SCOPE; }; =20 +union access_masks_all { + struct access_masks masks; + u32 all; +}; + +/* Makes sure all fields are covered. */ +static_assert(sizeof(((union access_masks_all *)NULL)->masks) =3D=3D + sizeof(((union access_masks_all *)NULL)->all)); + typedef u16 layer_mask_t; /* Makes sure all layers can be checked. */ static_assert(BITS_PER_TYPE(layer_mask_t) >=3D LANDLOCK_MAX_NUM_LAYERS); @@ -260,6 +269,58 @@ static inline void landlock_get_ruleset(struct landloc= k_ruleset *const ruleset) refcount_inc(&ruleset->usage); } =20 +/** + * landlock_merge_access_masks - Return the merge of a ruleset's access_ma= sks + * + * @ruleset: Landlock ruleset (used as a domain) + * + * Returns: an access_masks result of the OR of all the ruleset's access m= asks. + */ +static inline struct access_masks +landlock_merge_access_masks(const struct landlock_ruleset *const ruleset) +{ + union access_masks_all matches =3D {}; + size_t layer_level; + + for (layer_level =3D 0; layer_level < ruleset->num_layers; + layer_level++) { + union access_masks_all layer =3D { + .masks =3D ruleset->access_masks[layer_level], + }; + + matches.all |=3D layer.all; + } + + return matches.masks; +} + +/** + * landlock_match_ruleset - Return @ruleset if any @masks right matches + * + * @ruleset: Landlock ruleset (used as a domain) + * @masks: access masks + * + * Returns: @ruleset if @masks matches, or NULL otherwise. + */ +static inline const struct landlock_ruleset * +landlock_match_ruleset(const struct landlock_ruleset *const ruleset, + const struct access_masks masks) +{ + const union access_masks_all masks_all =3D { + .masks =3D masks, + }; + union access_masks_all merge =3D {}; + + if (!ruleset) + return NULL; + + merge.masks =3D landlock_merge_access_masks(ruleset); + if (merge.all & masks_all.all) + return ruleset; + + return NULL; +} + static inline void landlock_add_fs_access_mask(struct landlock_ruleset *const ruleset, const access_mask_t fs_access_mask, @@ -295,19 +356,12 @@ landlock_add_scope_mask(struct landlock_ruleset *cons= t ruleset, ruleset->access_masks[layer_level].scope |=3D mask; } =20 -static inline access_mask_t -landlock_get_raw_fs_access_mask(const struct landlock_ruleset *const rules= et, - const u16 layer_level) -{ - return ruleset->access_masks[layer_level].fs; -} - static inline access_mask_t landlock_get_fs_access_mask(const struct landlock_ruleset *const ruleset, const u16 layer_level) { /* Handles all initially denied by default access rights. */ - return landlock_get_raw_fs_access_mask(ruleset, layer_level) | + return ruleset->access_masks[layer_level].fs | LANDLOCK_ACCESS_FS_INITIALLY_DENIED; } =20 diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c index f5a0e7182ec0..c097d356fa45 100644 --- a/security/landlock/syscalls.c +++ b/security/landlock/syscalls.c @@ -329,7 +329,7 @@ static int add_rule_path_beneath(struct landlock_rulese= t *const ruleset, return -ENOMSG; =20 /* Checks that allowed_access matches the @ruleset constraints. */ - mask =3D landlock_get_raw_fs_access_mask(ruleset, 0); + mask =3D ruleset->access_masks[0].fs; if ((path_beneath_attr.allowed_access | mask) !=3D mask) return -EINVAL; =20 --=20 2.47.0